Lol I'm 40% sure this is a joke, but in case it isn't: if you place conductors in the microwave: sometimes it's a spoon, sometimes it's the silver lining on a plate, or you can go overboard and throw actual aluminum foil in there for good measure...the microwaves drive a current in the conductor **, which creates sparks from lots of tiny arcs...lightning indeed my friend :D

Suggestion: Forks are particularly spectacular too

PS: the foil should act as shielding against the microwaves, so I predict that the content won't warm up, but maybe the hole is enough to let it heat it a bit :)

** If a conductor is not convex (e.g. fork, crinkled aluminum foil), each crease acts as a capacitor, so when the microwaves drive (through resonance) a current and overcharge the capacitor plates, they short the dielectric (the air in this case) and create the arcs.